Interview with William O’Neil
A team at Henry Ford Hospital, Detroit, USA, has successfully performed the first transcatheter tricuspid valve replacement surgery in the USA. William O’Neill, medical director, Center for Structural Heart Disease, Henry Ford Hospital, speaks to Cardiovascular News about the procedure, which was pioneered in a five-patient study in Germany, and the potential for a new device design specifically for transcatheter tricuspid valve replacement.
What are the limitations of the open tricuspid valve surgery?
The patients that need the therapy are often the sickest. They are older, they have a lot of liver abnormalities because of the high hepatic pressure and are generally quite disabled. So having heart surgery with the sternotomy and bypass causes a lot of morbidity and complications. Surgeons, therefore, are reluctant to operate just isolated on tricuspid valves.
You and your team at Henry Ford Hospital were the first in the USA to perform transcatheter tricuspid valve replacement. Please can you describe this procedure?
Our patient at Henry Ford Hospital was a lady in her mid 50s. She experienced two previous open heart operations and had prior chest radiation. Therefore, she was not really eligible to have another open heart operation, and her tricuspid valve failed.
As a result, she had problems with severe swelling in her legs and severe congestion of her liver. The Henry Ford team placed a valve at the junction of the inferior vena cava and the right atrium so that the organs of the abdomen were protected from high pressures. When the tricuspid valve does not work, when the right ventricle pumps, it pumps most of its blood backwards into the right atrium and into the vena cava. So by the Henry Ford team putting the valve right at the junction of the vena cava and the right atrium, we actually blocked the high pressures from the right ventricle.
How did the use of 3D modelling help you to plan the procedure?
The 3D modelling by the Henry Ford Innovation Institute really allowed us first to find out the best angle to put our X-ray catheters. We knew exactly what positions would be best to find the origin of the hepatic veins so we did not block the them. The Henry Ford team also used the model for sizing, to try to figure out exactly the sizes of stents and the size of the valve that was going to be deployed.
How can a TAVI device placed outside the heart inside the inferior vena cava do the work of the tricuspid valve?
Basically, the tricuspid valve sits at the outflow of the right atrium. When that does not work, then high pressures go into the right atrium and they are transmitted backwards into the vena cava. We figured if we put a valve at the origin of the vena cava, that there would not be as much back pressure when the right ventricle contracts. So basically it is just blocking severe pressure elevations into the vena cava.
The procedure was pioneered in Germany. What data are available for this approach?
There was one study that was published with five patients in Germany.
How is the patient who underwent the procedure now doing?
She was discharged from Henry Ford Hospital about three days after the procedure and we are keeping a very careful eye on her to make sure she does not develop complications. She required one hospitalisation for some fluid in her lungs, but that is all being treated now.
Which patients would be most suited to undergoing this approach?
People most suited to this approach are those with severe tricuspid valve regurgitation who have other comorbidities that make heart surgery not feasible.
What are the potential complications of this approach?
Potential complications are clots that could occur in the vena cava and potential migration of the valve; it might move.
Given the successful outcomes observed in this case, are there any studies of this approach planned in the near future?
Brian O’Neill at Temple University is going to be doing a national FDA-approved trial to demonstrate on a large-scale basis whether the procedure is safe and works.
Is the type of TAVI device relevant? For example, is a balloon-expandable valve better suited to the approach than a self-expanding valve or vice versa?
I think the balloon-expandable valve is better made. We used a 29mm Edwards Sapien valve.
If studies show that this is a successful procedure, do you think a device could be designed specifically for procedure? If so, what would be the features of such a device?
It is going to have to be shorter in length because a lot of hepatic veins come off of the inferior vena cava very close to the origin of the right atrium. It is also going to have to be wider because often the vena cava is very wide. Those are the two things that are going to be required.
Do you think that, potentially, transcatheter tricuspid valve replacement could progress to the stage in which a bioprosthetic valve is implanted within the damaged valve itself as with TAVI?
Yes. I think the specifically designed valves with bioprosthetic leaflets will work. It is just a matter of finding the right construct so that it can sit in the origin of the right atrium without embolising.